Greasy Fork

Little revision:

(function () {
  "use-strict";

  let observer = new MutationObserver((mutations) => {
    mutations.forEach((m) => {
      m.addedNodes.forEach((node) => {
        node.querySelectorAll("img[alt='PogChamp']").forEach((img) => {
          img.src = img.srcset = "https://cdn.betterttv.net/emote/5ff8cf3194ed120c66d3bb9e/3x";
        });
      });
    });
  });

  function observeDOM() {
    observer.observe(
      document.querySelector("div.chat-scrollable-area__message-container"),
      {
        childList: true,
        attributes: true,
        subtree: true,
      }
    );
  }

  setTimeout(observeDOM, 3000);
})();